The present invention relates to a wear resistant sintered body for use in a blade or the like of a rotary compressor, and to a method for manufacturing the same.
A rotary compressor is used for an air conditioner, a shop window display case or the like and has a structure as shown in FIG. 1. Referring to FIG. 1, a rotor 2 eccentrically rotates within a cylinder 1 and in contact with a blade 3. The blade 3 is constantly urged against the rotating rotor 2 and reciprocates in accordance with the rotation of the rotor 2, thereby partitioning the interior of the cylinder 1. For this purpose, the blade 3 must be air-tight and must also have a high wear resistance. The wear at that portion of the blade 3 which is in contact with the rotor 2 and with the cylinder 1 is generally significant.
Accordingly, most conventional blades of a rotary compressor of the type described above are made of a material with an improved wear resistance, such as high-speed steel or eutectic graphite cast iron. Japanese Patent Publication No. 57-9421 (Published on Feb. 22, 1982) discloses a technique of treating a sintered body of an iron-based powder with steam to give the body improved wear resistance and air-tightness.
Some air conditioners are operated under severe conditions, e.g., in Middle and Near East countries, or with an inverter. Thus, a rotary compressor used in such an air conditioner must operate under severe conditions such as those occurring in high-speed operation or variable-speed operation. The blades of the rotary compressor must also have a higher wear resistance than conventional blades for high-speed operation.
However, a conventional blade consisting of a casting material or a sintered body does not have a high abrasion resistance to withstand use under severe operating conditions, and cannot therefore be used in numerous practical situations.